The monthly sales of mufflers in the Richmond, Virginia, area follow the normal distribution with a mean of 1,200 and a standard deviation of 225. The manufacturer would like to establish inventory levels such that there is only a 5 percent chance of running out of stock. Where should the manufacturer set the inventory levels? Denote X to be the random variable "monthly sales of mufflers", and x to be the right inventory level the manufacturer sets, choose from the followings the correct way to set up for x:

a. P(X<=x) = 0.05

b. P(X<=x) = 0.95

c. x = P(X<=1200)

d. x = P(X<=225)

e. x = P(X<=0.05)